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I can't get the tach to work properly. I have "followed" the brown wire from the tack to the negative side of the coil and the connection is good. There are a couple of wires (brown and black ) coming out of the back of the tach that are not connected - should they be ( i have standard ign.) What am I missing? Also, I cannot find the a wiring diagram for the rally gauges - where can i find one?? . Any and all help is appreciated. Thanks:confused
 

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last I checked there was no separate wiring diagram for gauges since the wiring is the same, only the senders get changed for gauges since the harness connects properly to lamps or if replaced by gauge setups, using correct circuit board.
 

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The wiring diagrams I have don't have a tach on them. Is there a seperate connection/sender between the tach and the coil for 65 ? There is a spade connector ( not sure what it's called - its flat) with brown and black wires - is that for electronic ignition?
 

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Go to the PY forum..look up Peter Serio....he will know the answer. Pete restores dashes and shifters...great guy. he built my dash panel for my 67 GTO...it LOOKS and WORKS great! Eric
 

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Old thread, but would clarification.....So the original gauge just has a plug for the negative side of the coil and then is grounded via the bulbs / chassis.

I have a "new gauge" from Ames that has a "+" terminal and "S" terminal. I am guessing the "S" goes to the negative side of the coil and the "+" gets a switched 12v + ?
 

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Old thread, but would clarification.....So the original gauge just has a plug for the negative side of the coil and then is grounded via the bulbs / chassis.

I have a "new gauge" from Ames that has a "+" terminal and "S" terminal. I am guessing the "S" goes to the negative side of the coil and the "+" gets a switched 12v + ?
From the 65 Pontiac Shop Manual if it helps...
 

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5/5/19 Update: installed the replacement gauge, installed the dash, and fired up the car....DOA...Called Ames Performance and they now claim (+) is to keyed source and (S) is Signal, but unlike the original needs to be routed to the negative side of the coil (???). I ran a jumper wire to negative side of coil to S and still nothing....

So a few points: (1) no instructions with the replacement gauge, (2) not wired like original , (3) Ames Performance has given conflicting tech support :(.
 

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Another quick update and buyer beware - the tachometer I bought from Ames Performance is defective. Furthermore, Ames Performance basically has been of no help and wants meet send them back the unit for "inspection" before sending me a replacement. Obviously this is frustrating as Ames Performance is nothing more than a distributor and won't be able to do any sort of diagnosis or repair or calibration.

Given that I have spent thousands of dollars with them and they treat me like an ant just kills me. Poor customer service will kill any business, especially a business that is just a distributor.

So as I have stated, buyer beware with Ames. If you can't find the manufacturer of a part needed (with knowledgeable staff), use OPGI or The Parts Place.....Just my opinion, yours may vary.
 

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Question - for an original single wire tach, is the coil connection positive side or negative side? I have seen a couple of forum people saying neg but the diagram from Hickman shows positive. Thanks
 

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Question - for an original single wire tach, is the coil connection positive side or negative side? I have seen a couple of forum people saying neg but the diagram from Hickman shows positive. Thanks
Tach signal wire will always be coil negative. The positive side of the coil is always hot with the key forward (otherwise known as accessory 12v or run) position, providing no useful information to the tach. Its either that or a tach signal wire from an hei distributor or digital ignition such as an msd box.
 

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Negative side is what I remembered but Hickboys posting showing the shop manual page is evidently in error. I wonder how many tachometers were destroyed using this as a guide?

The reason I brought this up is that my tach worked before my engine overhaul. Now with the fresh rebuild the tach is not working when wired to negative and I was not going to use the positive feed unless absolutely verified. Btw I am on point ignition. 1965 gto
 

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Question - for an original single wire tach, is the coil connection positive side or negative side? I have seen a couple of forum people saying neg but the diagram from Hickman shows positive. Thanks
Negative
 

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Hickboys pick is not for a GTO. Look close at the PIC. All standard ignition point cars with tachs picked up signal from neg side of the coil. The Rare Transistorized ignition used the + side of coil and the 65 TI tach would have 2 red grommets for 2 connections.
 

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